Yep, the MKIII was made from 1969-1982 while the MKV was made from '82-'85 (although some were shipped in early '86 before the strike). There were Trooper MKIII's made in 1983 with vented rib barrels. After the MKIII was discontinued, Colt discovered it had enough MKIII components (less barrels) to make complete guns so Colt decided to fit the vented MKV barrel to the MKIII frames. Here is my MKIII with a MKV vented barrel roll-marked MKIII.Is the the value of the Mk V that much greater than a Mk III? I just fell into an awesome deal on a really nice Mk III and was curious as to difference between the two other than the vent rib.